A variety of apparatuses and methods are known in the field of orthopedics for reducing, fixing and generally assisting the healing of fractured bones. In some cases, these apparatuses and methods require surgical intervention. Open reduction internal fixation (ORIF) is a developed art with respect to some portions of the body; however, many complications can exist which can prevent successful or optimal outcomes in all cases utilizing ORIF. Treatment methods can also significantly impact healing time, pain and functional outcomes. Moreover, the necessity of reducing operative time is driven both by patient risk of infection, and aesthetic complications, and health care costs. Thus, efforts continue to be made to improve fixation devices and surgical techniques in an attempt to improve surgical outcomes, costs and operative times.
Several factors are considered to be well known which can have significant impact in predicting outcomes of ORIF. These factors include:                1. Prominence of hardware, leading to soft tissue abrasion and general inflammation.        2. Accurate reduction of fracture site providing proper alignment in all degrees of freedom.        3. Reliable fixation that rigidly approximates bone segments during healing.        4. Production of adequate and predictable compression across fracture sites which provides impetus for improved healing.        5. Minimization of skin incision and exposure to patient.        6. Reduced operative times.        
Thus, it is desirable to utilize a fracture fixation apparatus and method which provides for low-profile hardware, or hardware countersunk into bone, which reduces or eliminates soft tissue abrasions and inflammation. Additionally, it is desirable to utilize an apparatus and method that provides for reproducible reduction, fixation, and also accurate bone compression to optimize the healing process. Such an apparatus and method must also minimize skin incision and provide a method that is simple and timely in terms of operating room resources and patient risk. Since fractures can occur in all bones of the body, both large and small, it is further desirable to utilize a consistent apparatus and method that can be used and scaled to fit all size applications regardless of the size of a bone fracture.
Fixation plates are common apparatuses used in orthopedic surgery for fixing two or more bone fragments together. Commonly, a plate with several holes defined in the plate is placed adjacent to bone fragments, and screws are driven through the plate holes and into the bone fragments. This method can often provide a satisfactory reduction and fixation where sufficient bony material is available for firmly grasping and orienting a screw/plate construct. More specifically, when a fixation apparatus is able to penetrate and engage two bone cortices, the fixation apparatus is firmly supported in two locations and will thus be rotationally aligned with the plate. If the fixation apparatus is, however, only able to grasp one cortice, and in a normal case, the proximal cortice, rotational alignment is not firmly engaged between the fixation apparatus and the plate and accurate reduction of the fixation site may not be maintained. This problem is also common in the areas of the body not involving particularly long bones, such as the hand, foot and spine. This problem also commonly exists in unhealthy (rheumatoid or osteoporotic) bone that simply cannot purchase bone as firmly as healthy bone.
A variety of apparatuses and methods have existed and exist in the prior art relating to bone fracture repair. The first generation of designs for screw/plate hardware used in fracture repair consisted of simply designed mechanisms using conventional hardware and materials compatible with the application. There was little effort to reduce the profile to protect soft tissue or control the position. The second generation added to the technology of the first generation by simply making allowance for the screw to sit into the profile of the plate (countersunk) so that soft tissue abrasion was minimized.
The third generation utilized a spherical countersunk screw in plate design as it became evident as plates were used more widely through the body that it was desirable to allow the screw to be positioned in many or a range or angles relative to the plate. By creating a sphere and globular socket mechanism, a solid construct could be obtained with the screw at any angle to the plate. The fact that the screw can engage two cortices allowed the angle to be fixed. The fourth generation utilized a fixed angle countersunk screw in plate design as screw and plate mechanisms were continually used in smaller and more complex regions of the body. There was a need to be able to hold bony structures rigidly in situations where little inherent support was available. A fixed angle between the screw and plate was created by threading the head of the screw into the plate. The angle of the screw relative to the plate was determined at manufacture of the hardware. This technology is represented at least in part by U.S. Pat. No. 6,440,135 to Orbay et al.
One invention currently sold under the mark PEAK by DePuy Acromed (Raynham, Mass.) is disclosed in U.S. Pat. No. 5,954,722 to Bono. The apparatus described in this patent utilizes a plate with holes which have spherical diameter bores into which fit spherical outer diameter bushings. The bushings have a tapered, threaded inner diameter, and a specially designed screw is available that has a tapered head matching that of the bushing. As the screw is driven through the bushing, the threads engage and produce a radial force in the bushing, pushing against the inner wall of the plate. The alignment of the screw to the plate is held with a moment corresponding to the amount of friction between the bushing and the plate. Primary shortcomings of this apparatus include:                1. The angle of the screw must be determined prior to insertion of the screw.        2. The screw cannot optionally be allowed to remain unlocked as a locking construct must be used.        3. The locking mechanism requires careful planning upon insertion as long as there is propensity for “cross-threading” the construct due to its fine thread and long length.        4. Compression of bone with the screw independent of locking the screw in place is either not possible or is limited.        